Took mine to the dealer today for same problem. They said there is debris in the cooling lines/heater core. They are replacing the heater core. They also said there was debris in the radiator that looked like internal decomposition so they're replacing the radiator as well. Glad its all covered but scary there are so many problems with this. Hope this fixes mine.

Took mine to the dealer today for same problem. They said there is debris in the cooling lines/heater core. They are replacing the heater core. They also said there was debris in the radiator that looked like internal decomposition so they're replacing the radiator as well. Glad its all covered but scary there are so many problems with this. Hope this fixes mine.

Update on mine... Took it in for a one day fix, not so much. To replace the heater core they have to take the whole freakin' dash off. Saw it sitting in the engine block under the hood. Not a pretty sight. Anyway, not a one day job and they put me up in a Gucci Fiat for 4 days. Yup. By the way, I'm 6'1", 240 lbs. and look like a clown in a Fiat. I'm very unnerved that my brand new Jeep had to be taken apart, but they replaced the heater core and radiator. Said there was "casting sand" in there from the manufacturing of the parts. The heat seems to be working fine, I guess, but I'm apprehensive. I will advise if anything changes! My advice is, if your heat isn't blasting hot, take it in! Its new and it should.

I had the exact same problem in My '08 JKU: No heat on driver's side and scalding hot on Pass. Dealer replaced the heater core. Thank GOD it was under warranty at the time. It was at dealer for 4 days and took at least 12 hours to repair. They had the remove the dash and the intake to change the core. Plus they didn't order all of the parts the first time. They had never heard of this happening before and had no explanation for why it failed. Check your heat before the warranty goes out. You do not want this bill!

It is a heater door that is warped and not opening. If there is heat on one side the core is fine. If they replaced the core and it works it's because they had to remove the door or mess with it and when they put it back together they fixed the door without knowing it. IMO

It is a heater door that is warped and not opening. If there is heat on one side the core is fine. If they replaced the core and it works it's because they had to remove the door or mess with it and when they put it back together they fixed the door without knowing it. IMO

Hey guys thanks for all the useful info. I'm hoping this thread is enough evidence to take in and prove the dealership wrong. It's strange though, now since I got the jeep back, it's a little better, only does the half hot/half cold thing about half as much as it uses to. But it constantly fogs up my windows now. Ill turn on the defroster and wait for the condensation to clear, then switch back to vents and then I get freezing cold air again... Also getting that syrupy antifreeze smell. So is my problem most likely a bad heater core AND the little door too?

Hey guys thanks for all the useful info. I'm hoping this thread is enough evidence to take in and prove the dealership wrong. It's strange though, now since I got the jeep back, it's a little better, only does the half hot/half cold thing about half as much as it uses to. But it constantly fogs up my windows now. Ill turn on the defroster and wait for the condensation to clear, then switch back to vents and then I get freezing cold air again... Also getting that syrupy antifreeze smell. So is my problem most likely a bad heater core AND the little door too?

Oh no... scary reply nickmonaco. Mine also seems a little better but I would expect hotter from a brand new vehicle. Its only like 45 degrees here and it takes a long time to warm the compartment. Also, my windows also fogged today and I didn't think anything of it... until I read your post! Something is definitely wrong here, I think. Plus, good point from an earlier post by someone: If its hot on one side and not the other, its not the heater core.

It is a heater door that is warped and not opening. If there is heat on one side the core is fine. If they replaced the core and it works it's because they had to remove the door or mess with it and when they put it back together they fixed the door without knowing it. IMO

How does that explain their findings that the cores are clogged with sediment and casting sand rendering them partially useless and needing replacement?

Bad snow storm in Northwest PA, just took my '12 Wrangler to town, heat only comes out right side and cold on left. I called dealer for appointment for this Friday. I read some of this forum's discussion points. He said if heat coming out of one side, must be difuser. I told him the heat coming out of passenger side is only about 50-75%. Only 6,500 miles. We shall see what happens - Can't go without heat when our avg. temperature for next 3 months will be about 30 degrees.